The World Health Organization (WHO) on Wednesday, said it has approved a COVID vaccine by Sinovac Biotech for emergency use, making it the second Chinese shot to be given the green light.

"WHO today validated the Sinovac-CoronaVac COVID-19 vaccine for emergency use, giving countries, funders, procuring agencies and communities the assurance that it meets international standards for safety, efficacy and manufacturing," the WHO said in a statement.

Last month, Sinopharm became the first Chinese vaccine to be approved by the WHO.

Dubbed as CoronaVac, it is an inactivated vaccine which is recommended for use in adults 18 years and older, in a two-dose schedule with a spacing of two to four weeks.

Its easy storage requirements make it very manageable and particularly suitable for low-resource settings, the WHO said.

The COVID-19 vaccine has already been granted emergency authorisation in several countries including, Indonesia, Turkey, Brazil and Mexcico.

The WHO said the efficacy results showed that the vaccine prevented symptomatic disease in 51 percent of those vaccinated and prevented severe COVID and hospitalisation in 100 percent of the studied population.

The WHO's Strategic Advisory Group of Experts on Immunisation have reviewed the jab and published their advice on its usage.

CoronaVac has battled concerns over its efficacy after the shot’s clinical trials across Brazil, Turkey and Indonesia put the vaccine’s efficacy anywhere between 50 percent to over 90 percent, according to Bloomberg.

Researchers in Turkey said it is 91.25 percent effective in trials which included over 7,000 volunteers, but the efficacy result was based on data from 1,322 people, Reuters reported.

Indonesia said the vaccine is 65 percent effective based on trials involving some 1,600 people.

According to experts, prevalence of the virus in each site, trial size, patient criteria, duration of post-vaccination observation, target groups among others could impact efficacy.

While the divergent efficacy rates have contributed to suspicions, evidence emerging in the real world is widely positive.

Last month, Indonesia said that its study of 130,000 healthcare workers in Jakarta who had received the vaccine found it was 94 percent effective at preventing symptomatic infection, and cuts hospitalisation and death by 96% and 98% respectively, rates comparable to mRNA vaccines, Bloomberg reported.

On Monday, Brazil announced that a study in which an entire town received CoronaVac found that deaths from Covid there had dropped 95 percent.

Chile’s real-world data shows CoronaVac prevented 80 percent of deaths in those vaccinated and protected 67 percent from developing symptomatic infection.

WHO granting emergency use for CoronaVac paves the way for countries worldwide to quickly approve and import a vaccine for distribution.

WHO’s Emergency Use Listing (EUL) is a prerequisite for COVAX Facility vaccine supply and international procurement.

The WHO approval also paves the way for countries to allow travelers who have received Sinovac shots, even if the vaccine isn’t approved for use locally.

(With inputs from Reuters and Bloomberg)